1. Field of the Invention
The present invention relates to alarming apparatus and method for an automotive vehicle.
2. Description of the Related Art
Japanese Patent Application First Publications No. Heisei 11-34696 published on Feb. 9, 1999 and Heisei 10-119673 published on May 12, 1998 exemplify first and second previously proposed alarming apparatuses applied to automotive vehicles.
In the former above-described Japanese Patent Application First Publication (JP1134696), the vehicle is too approaching to the preceding vehicle in a case where another vehicle is interrupted into a space as a new  preceding vehicle between the vehicle and the old preceding vehicle. At this time, a blink of an alarm lamp or a sound of an alarm buzzer is activated to inform the driver of such an abrupt approach to the other vehicle as described above so that the driver is forcefully pressed to manipulate a brake system of the vehicle.
The latter above-described Japanese Patent Application First publication (JP10119673) discloses a technique in which a predicted arrival time duration for the vehicle to arrive at an obstacle on the basis of an obstacle information and vehicular information is calculated and an alarm device is activated on the basis of a relationship between an alarm timing and the predicted arrival time in terms of a time concept.
However, in the previously proposed alarming apparatus disclosed in the former Japanese Patent Application Publication, a determination of whether the vehicle is about to collide against a rear portion of the preceding vehicle is set in accordance with such a deceleration as would be developed by means of a preceding vehicle following adaptive vehicular velocity control apparatus.
For example, in a case where the inter-vehicle distance from the vehicle to the preceding vehicle indicates such an inter-vehicle distance as requiring the deceleration equal to or larger than 0.2 G, the previously proposed alarming apparatus issues an alarm to the vehicle driver.
In other words, no consideration of a road surface frictional coefficient of a road surface on which the vehicle is running is taken but only the alarm-in accordance with the inter-vehicle distance to the preceding vehicle and the relative velocity is issued. Even if the vehicle is running on a road surface having a low road surface frictional coefficient, the alarm is issued at the same timing as the vehicular run on a high frictional coefficient.
The alarm at this timing is effective in terms of avoidance of the vehicle from a possible collision against the preceding vehicle.
However, for example, in cases where the deceleration of 0.15 G is developed during the vehicular run on the road surface having the road surface frictional coefficient of 1.0 and where the same deceleration of 0.15 G is developed during the vehicular run on the road surface having the road surface frictional coefficient of 0.3, the same deceleration of 0.15 G can be developed and the alarm is not issued since 0.15 G is smaller than 0.2 G.
Actually, however, a safety margin of the vehicle is different in such a way as the margin becomes smaller, as the frictional coefficient of the road surface on which the vehicle is running becomes lower. It is difficult for the vehicle driver to recognize this state when the vehicle is running on the road surface having the low frictional coefficient.
On the other hand, in the vehicular alarming apparatus disclosed in the latter Japanese Patent Application first Publication, no consideration of the frictional coefficient of the road surface on which the vehicle is running is taken but only the alarm is issued in accordance with a predicted arrival time duration toward an obstacle placed in the forward direction.
For example, in a case where the inter-vehicle distance between the vehicle and the preceding vehicle and the relative velocity of the vehicle to the preceding vehicle are the same, the same predicted arrival time durations are resulted where the vehicle is running on the road surface having the low road surface frictional coefficient and having the high road surface frictional coefficient and the alarm is issues at the same timing.
Hence, the timing at which the alarm is issued becomes delayed when the vehicle is running on the road surface of the low frictional coefficient having the small vehicular safety margin. It is difficult for the vehicle driver to recognize such a situation as described above when the vehicle is running on the low frictional road surface.
It is an object of the present invention to provide alarming apparatus and method for an automotive vehicle which can have the vehicle driver recognize that a vehicular safety margin is reduced at an appropriate timing irrespective of a magnitude of the road surface frictional coefficient.
According to one aspect of the present invention, there is provided an alarming apparatus for an automotive vehicle, comprising: a running state detector to detect a vehicular running state; a road surface frictional coefficient detector to detect a frictional coefficient of a road surface on which the vehicle is running; a vehicle using road surface frictional coefficient calculating section that calculates a vehicle using road surface frictional coefficient that corresponds to a road surface frictional force the presently running vehicle is using on the basis of the detected vehicular running state; a road surface frictional coefficient utilization rate calculating section that calculates a road surface frictional coefficient utilization rate which is a rate of the calculated vehicle using road surface frictional coefficient of the road surface to a maximum frictional coefficient detected by the road surface frictional coefficient detector; and an alarm controlling section that outputs an alarm command to an alarm device to issue an alarm when the calculated road surface frictional coefficient utilization rate is equal to or larger than a set value.
According to another aspect of the present invention, there is provided an alarming method for an automotive vehicle, comprising: detecting a vehicular running state; detecting a frictional coefficient of a road surface on which the vehicle is running; calculating a vehicle using road surface frictional coefficient that corresponds to a road surface frictional force the presently running vehicle is using on the basis of the detected vehicular running state; calculating a road surface frictional coefficient utilization rate which is a rate of the calculated vehicle using road surface frictional coefficient of the road surface to a maximum frictional coefficient detected at the frictional coefficient detection; and outputting a command to an alarm device to issue an alarm when the calculated road surface frictional coefficient utilization rate is equal to or larger than a set value.
According to a still another aspect of the present invention, there is provided an alarming apparatus for an automotive vehicle, comprising: running state detecting means for detecting a vehicular running state; road surface frictional coefficient detecting means for detecting a frictional coefficient of a road surface on which the vehicle is running; vehicle using road surface frictional coefficient calculating means for calculating a vehicle using road surface frictional coefficient that corresponds to a road surface frictional force the presently running vehicle is using on the basis of the detected vehicular running state; road surface frictional coefficient utilization rate calculating means for calculating a road surface frictional coefficient utilization rate which is a rate of the calculated vehicle using road surface frictional coefficient of the road surface to a maximum frictional coefficient detected by the road surface frictional coefficient detecting means; and alarm controlling means for outputting a command to an alarm device to issue an alarm when the calculated road surface frictional coefficient utilization rate is equal to or larger than a set value.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.